netdev - Re: [PATCH ipsec] xfrm: prevent ipcomp scratch buffer race condition

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Message-ID: <20131016123205.GA9982@gondor.apana.org.au>
Date:	Wed, 16 Oct 2013 20:32:05 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Michal Kubecek <mkubecek@...e.cz>
Cc:	Steffen Klassert <steffen.klassert@...unet.com>,
	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH ipsec] xfrm: prevent ipcomp scratch buffer race condition

On Mon, Oct 14, 2013 at 06:03:34PM +0200, Michal Kubecek wrote:
> In ipcomp_compress(), sortirq is enabled too early, allowing the
> per-cpu scratch buffer to be rewritten by ipcomp_decompress()
> (called on the same CPU in softirq context) between populating
> the buffer and copying the compressed data to the skb.

Good catch.

> Add similar protection into ipcomp_decompress() as it can be
> called from process context as well (even if such scenario seems
> a bit artificial).

I don't think this is possible or otherwise xfrm_input will
dead-lock.

Thanks,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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